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蒸散量量是地表水分循循环的重要分量量,与农业和生态系统的水水分需求密切相相关,是水资源规规划和管理必须考虑的重要要因素之一.虽虽然对湿润区作作物蒸散计算模型研究已经经相对比较成熟熟,但但由于干旱和半干旱区作物物蒸散量受干旱旱胁迫的显著著影响,以往建建立的湿润区作作物蒸散模型和作作物系数并不适用对其作物物蒸散量的估算算,而目前对这一问题的研研究却十分有限限.利用位于黄土土高原典型半干旱区的“定西西干旱生态环环境综合科学试试验站”春小麦麦农田的蒸渗仪仪、蒸发皿、超声声涡动仪的观测资料及常规规气象观测资料料相结合,分析了该地区实际蒸散量与F AO推荐作物系数数估算的蒸散量之间的差异异性及其随干旱旱胁迫度的变化关系.研究究了该地区春小小麦参考蒸散量与与蒸发皿蒸发量比值和实际际蒸散量与蒸发发皿蒸发量比值随干旱胁迫迫度的变化特征征及春小麦作物系系数对干旱胁迫度的响应规规律,并对FA O推荐值的作作物系数进行了改进.分析发现,由于半干旱旱区作物蒸散受干旱胁迫影影响较大,FAO推荐作物系数数估算的蒸散散量与实际蒸散散量相差很显著著,实实际作物系数对干旱胁迫度度的依赖很强,,随干旱胁迫度增加显著减减少,但其敏感感性在干旱胁迫度度约达到0.7后明显降低.而且,改进的作物系数在作作物生长初期和和发育期远远低低于FAO的推荐荐值和Kumar修正值,改进进的作物系数估估算的春小麦蒸散量也明显显比后两者估算算的更接近实际观观测值,与观测测值线性拟合的系数为0.98,决定系数能能够达到0.455,标准误差也也仅为0.85 mm m,对对半干旱地区春小麦蒸散量量的估算效果比比较理想.
The amount of evapotranspiration is an important component of the circulation of surface water and is closely related to the water and moisture requirements of agriculture and ecosystem, which is one of the most important factors that must be considered in the planning and management of water resources regulation. Although crop evapotranspiration Computational modeling studies have been comparatively mature, but the evapotranspiration model and crop coefficient built in the former wetlands are not suitable for crop evapotranspiration in arid and semi-arid regions due to the significant impact of drought stress. Crop evapotranspiration estimates, and the current research on this issue is very limited.Using the typical semi-arid zone in the Loess Plateau “Dingxi West Drought Ecological Environment Experimental Station ” spring wheat and wheat fields , The evaporation data from evapotranspiration vessel and ultrasonic vortex instrument, and the conventional meteorological observation data, the differences between the actual evapotranspiration and the evapotranspiration estimated from F AO recommended crop coefficient were analyzed And its relationship with the drought drought stress changes in the study of the region of spring wheat reference evapotranspiration and pan evaporation ratio and the actual amount of evapotranspiration and The ratio of evapotranspiration rate of panicle to drought stress and the response rule of spring wheat coefficient to drought stress were improved and the crop coefficient of FA O recommendation was improved.It was found that due to the semi-arid drought The crop evapotranspiration is greatly affected by drought stress, the estimated evapotranspiration estimated by the FAO recommended crop coefficient is significantly different from the actual evapotranspiration, and the actual crop coefficient is highly dependent on the degree of drought stress. With the drought stress But its sensitive sensitivity decreased obviously when the degree of drought stress reached about 0.7. Moreover, the improved crop coefficient was far lower than the FAO recommended value and Kumar’s correction value at the early stage of growth and the development stage , The estimated evapotranspiration of spring wheat estimated by improved crop coefficient was significantly more than the actual observations of the latter two. The coefficient of linear fit with observed values was 0.98, the coefficient of determination could reach 0.455, the standard error Which is also only 0.85 mm m. The estimation of spring wheat evapotranspiration in the semi-arid area is quite satisfactory.